Our hummingbirds don't like to share, so we have to place multiple small 2 ounce feeders throughout the yard. Once ants find the feeders, they track a lot of dirt and block the openings which discourages the hummingbirds. It also means we have to clean the feeders more frequently than normal.
We've devised several different DIY methods to deter the ants. Mentholatum ointment is by far our favorite method, which requires the least amount of effort.
We already use mentholatum ointment to deter ants in the house. When we see them coming in, we'll swab whatever crevice they've found with the ointment and the problem is fixed.
For our hummingbird feeders, we use a butter knife and lightly coat the top of the feeder and sides of the attached hanger. We don't apply a very heavy coat of ointment, just in case the hummer bumps into the feeder. Because there are oils in the ointment, they could impede a hummer's waterproofing if its feathers were to come in contact with the ointment. The ointment has endured many torrential downpours as well as scorching sun. We only have to reapply ointment when we deep-clean the feeders.
We've heard others have used Vapor Rub, which probably works just as well. But since we already use the mentholatum ointment for ants inside the house, it made sense to try it outside as well.
DIY Ant Moat Guard
The DIY hummingbird ant moat guard is simple to make and also works well in keeping ants off the hummingbird feeder. It make feeder cleanings easy because we don't have to worry about reapplying the mentholatum ointment after each washing. However, it does mean we have to routinely monitor the water levels in each of feeders throughout the day. The water in the ant moat guard evaporates fairly quickly in the heat of the summer. The water also tends to spill out a bit during high winds. The ants must keep a close watch on the water levels, because as soon as the water is gone the ants are back. But otherwise, it works really well.
All it takes is some metal wire, a bottle cap, some decorative beads (optional) and hot glue. Once you've assembled it and hung it up, fill the cap with water and you're done!
Full instructions on how to make the DIY ant moat guard can be found here.
Treated String Hummingbird Feeder Ant Deterrent
Another easy DIY ant deterrent for you hummingbird feeders. We made this hanger using nylon craft roping, some decorative beads, and a little hot glue which secures the loops inside the beads. If you have a heavier hummingbird feeder, you should probably use a heavy duty adhesive to secure the loops. But our feeders are only 2 ounces and the string hangers have held up for two seasons without issue.
After you've assembled your string hanger, apply a decent coat of mentolatum ointment (or Vicks Vapor Rub) and work it into the entire string including the loops. This is the secret to keeping the ants from climbing down the string. The mentholatum deters the ants.
When you create your hanger, make sure that the middle section of the string is at least 3 inches long. The reason the minimum length is important is because ants will sometimes just drop down to avoid touching the ointment (we've seen them in action). The extra length helps ensure that most of them miss the feeder entirely. And for the few that make it to the feeder, they have to jump off eventually anyway, because they can't climb back up.
A few site recommend using monofilament fishing line as a hanger because the line is supposed to be too thin for ants to climb. We did try it, but apparently our ants went to acrobatics school and managed to climb up and down the fishing line without too much issue.